Amazon countered Apple's fourth-generation Apple TV announcement with new set-top box hardware of its own last week. Now there's mounting evidence suggesting Roku is next in line to unveil an updated media streamer.

A wealth of FCC filings recently hit the web, perhaps the strongest indication that new hardware is inbound.

Elsewhere, streaming company CinemaNow prematurely published information regarding an upcoming promotion that'll offer four free HD movie rentals with the purchase of a Roku 4. The promo lists a start date of October 1 and runs through April of 2016 which hints that Roku will likely unveil its new set-top boxes by the end of the month.

Last but not least, a Roku fan blog found mention of a 4K Showcase channel on Roku's website just ahead of Amazon's launch.

Both Apple and Amazon have traditionally taken an "unveil now, launch later" approach to their newest set-top boxes. Roku, on the other hand, usually releases its new hardware when announced. If that strategy holds true this time around, it's entirely possible that Roku could be the first to market with a next generation box as Amazon's 4K Fire TV and the latest Apple TV won't arrive until October 5 and late October, respectively.

Regardless of when it'll be announced, there's little denying that Roku's flagship box is due for an upgrade. The current high-end model, the Roku 3, launched more than two and a half years ago.